Published: 14 October 2024

In 2020, Alzheimer's Disease International estimated that the number of people living with dementia worldwide - nearly 55 million in 2020 - will almost double every 20 years. There is no single test that can show if a person has Alzheimer's, but doctors can almost always determine if a person has dementia, although it may be difficult to determine the exact cause. Diagnosing Alzheimer's requires careful medical evaluation, neurological testing, and sometimes brain imaging and blood tests to rule out other causes of dementia. Most of the testing for early disease - MRI scans of the brain, brain PET scans looking for amyloid, and spinal taps looking for certain proteins in the spinal fluid - are not very accurate, and they are invasive and often expensive. A few years ago, researchers have turned to findings in the eye to help with early detection and are hoping to find ways to make the diagnosis earlier when potential treatments may have a better outcome. There is also hope that these tests will be less expensive and invasive then the other options. One of the tests that has shown promise is an OCT of the retina. Almost every eye doctor’s office already has an OCT, and so if this research proves fruitful, the test could be done relatively cheaply because there is not a need to buy more expensive equipment. The average OCT exam costs much, much less than the cost of an MRI or PET Scan. Neuroscientists at the Gladstone Institutes in San Francisco showed a proof of concept in frontotemporal dementia, which is like Alzheimer’s but attacks much earlier and accounts for just 10% to 15% of dementia cases. They found that patients with frontotemporal dementia had thinning of the neuron layer of the retina on OCT. In a study at Moorfields Eye Hospital they also found that people who had a thinner layer of neurons in the macula on an OCT exam were more likely to perform poorly on the cognitive tests - a clear warning sign they may be undergoing the early stages of dementia. Study leader Dr. Fang Ko, said: “Our findings show a clear association between thinner macular retinal nerve fiber layer and poor cognition in the study population. This provides a possible new biomarker for studies of neurodegeneration.” A second marker that is getting a careful look is identifying the presence of amyloid in the eye. Amyloid, thought to be one of the key causes of Alzheimer’s, which makes up most dementia cases, is often found to have formed into clumps and plaques in the brain. Scientists at Waterloo University in Canada found people with severe Alzheimer’s disease had deposits of a protein amyloid on their retinas. Research conducted at Lifespan-Rhode Island Hospital in Providence co-led by Peter Snyder, a professor of neurology at Brown University, and Cláudia Santos, a graduate student at the University of Rhode Island, is attempting to detect amyloid in the retina by OCT and follows people over time to see if the amyloid increases and if it correlates with cognitive impairment. Another angle being pursued by a company called Cognoptix is looking for amyloid in the lens of the eye. Using Cognoptix's SAPPHIRE II system, which detects amyloid in the lens, a 40-person Phase 2 clinical trial was conducted at four sites. The study recruited patients who were clinically diagnosed with probable Alzheimer’s disease (AD) via a rigorous neuropsychological and imaging workup. The study, using age-matched healthy controls, showed outstanding results of 85% sensitivity, and 95% specificity in predicting which people had probable AD. One of the other items I was going to include in this post was information on what visual symptoms occur in dementia patients and how family and friends can support them but I found an outstanding review already available online by the Alzheimer’s society that covers all those points. If you have a loved one with dementia this is an excellent read and I highly recommend you take the time to review it. Article contributed by Dr. Brian Wnorowski, M.D.

Published: 28 September 2024

Have you ever wondered what happens to the visual system as we age? What does the term "second sight" mean? What is presbyopia? What are the eyes more susceptible to as the aging process occurs? What can be done to prevent certain aging factors of the eye? The answer lies in a theory known as apoptosis (no that's not the name of the latest pop artist). Apoptosis is the pre-programmed life of every cell in our body. Most studies show that it's a function of our programmed DNA. It's the ability for cells to survive and thrive in the anatomical environment. The body's ability to withstand and thrive during the aging process depends on proper nutrition, good mental health, exercise, and adequate oxygen supply. That's why studies have shown smoking can shorten your life by a decade or more. In regards to aging and the eye, there is a phenomenon during the 6th to 7th decade of life called "second sight." This is simply progressive nearsightedness in older adults secondary to cataracts. Close to 50% of the population over 60 years old has cataracts. Cataracts are a clouding of the natural lens of the eye that can impair vision, causing glare and loss of detail. When patients experience second sight, it is sometimes quite convenient for them--they see up close without the reading glasses they have been depended on since their 40s. Another aspect of the aging process is losing the reading vision you had all your life. This is called Presbyopia. Presbyopia is a Latin term which means "old eyes." What happens in Presbyopia? Before our mid-forties, the natural lens of the eye is very pliable and can easily focus on items up close. But in our mid-forties, the lens tends to lose its elasticity. When experiencing presbyopia, people generally hold reading material farther away to see it more clearly. Presbyopia can be managed through bifocal or multifocal glasses or contact lenses, and some surgeries. As aging occurs, the eyes are more susceptible to cataracts, glaucoma, macular degeneration and vascular disorders of the eye as well as dry eye syndrome. To help prevent and manage these conditions, there are a variety of options. Maintaining yearly dilated eye exams for preventative care. Protect your eyes against the sun with UV sunglasses. Take antioxidant vitamins to help bolster the protection of the macula. Use artificial tears to hydrate the eye and keep your body hydrated by drinking plenty of water. Keep emotional, physical, and mental stress to a minimum. Being educated on how we age is the first step towards good ocular health and diminished chances of early apoptosis. The content of this blog cannot be reproduced or duplicated without the express written consent of Eye IQ.